Harley is trying to get his dream job in Japan although he's already got a very good job as an English teacher, and he is doing an excellent job, I understand. However that is not what he really wants to do. So he has been applying for many job possibilities as a computer game developer. His Japanese is already very good, but he'd like to improve and make better job applications and trying his best. I believe it is not easy to receive letters of unsuccessful application; it is depressing, discouraging, disheartening and sometimes one loses one's confidence in oneself. Only one who has the same experiences can understand how one feels. It is a very hard time. However, I'd like him to keep his confidence up and believe in himself. ハーレーさん、頑張って下さいね!
Harley is now studying to improve his Japanese with an extremely high concentration to challenge a new phase of his life. I admire his efforts a lot. In the class, he had a bit difficulty saying 求(もと)められる。 It's just a matter of practicing. I hope he will practice saying it. And 現場(げんば)is not 「げんじょう」。
Well, for starters, you wouldn't say "the balls", It would just be "You have balls" or "You've got balls". And, as the other poster has said, I would not use this for women, for obvious reasons. Lastly, consider when you are saying this. Is this a formal situation, or just a casual situation with friends? If you're with guy friends, it's fine, but otherwise I wouldn't use it at any other time.